(1) Field of the Invention
This invention relates generally to a brain ventricle-peritoneum shunt or brain ventricle-auricle shunt (hereinafter called "brain ventricle shunt") surgically implanted in the body of a hydrocephalic patient or the like, and more especially, to a brain ventricle shunt which permits or facilitates a switch in the flow rate of the cerebro-spinal fluid.
(2) Description of the Prior Art
A brain ventricle shunt is generally constructed of a fine tubular brain ventricle catheter which is adapted to be inserted into the brain ventricle, a shunt main body (relay chamber) connected to the brain ventricle catheter and including a reservoir and a pump chamber, and a tubular peritoneum or auricle catheter connected to the shunt main body and which is adapted to be inserted into the peritoneum or the auricle.
The shunt main body is implanted on the skull under the scalp. Inside the shunt main body, there is provided a relief valve composed of a miter valve or the like, which is closed and opened by means of the pressure of the cerebro-spinal fluid, which is an excrement fluid from the brain ventricle. This relief valve serves to regulate the flow rate of the cerebro-spinal fluid owing to its function as a flow-rate regulator and also serves to function as a check valve.
Examples of conventional brain ventricle shunts are disclosed within U.S. Pat. No. 3,827,439 issued to Schulte at al. and entitled "Plug Valve For Physiological Shunt Systems" and U.S. Pat. No. 3,769,982 issued to Shulte and entitled "Physiological Drainage System With Closure Means Responsive to Downstream Suction".
On occasion, a need may arise to adjust the flow rate of the cerebro-spinal fluid, which is regulated by the above-mentioned check valve, after implantation of a brain ventricle shunt. Since the flow rate of the cerebro-spinal fluid is regulated at a fixed level due to the use of a single relief valve in a conventional brain ventricle shunt, the conventional brain ventricle shunt is accompanied by the problem that the shunt main body, which has been implanted in the head or the like of a patient, must be surgically removed so that its relief valve can then be replaced by means of another relief valve having a regulated flow rate of a different level.